/*
 * Copyright (c) 2011 Nathan Byrd
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 *    you may not use this file except in compliance with the License.
 *    You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *    Unless required by applicable law or agreed to in writing, software
 *    distributed under the License is distributed on an "AS IS" BASIS,
 *    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *    See the License for the specific language governing permissions and
 *    limitations under the License.
 */

package org.stackconfig.web.gwt.client.widgets;

import com.allen_sauer.gwt.dnd.client.DragContext;
import com.allen_sauer.gwt.dnd.client.VetoDragException;
import com.allen_sauer.gwt.dnd.client.drop.SimpleDropController;

/**
 * Controller to set down the component into a controller
 */
public class SetWidgetDropController extends SimpleDropController {
    private Component dropComponent;

    /**
     * Constructor
     *
     * @param dropComponent Component to drop into
     */
    public SetWidgetDropController(Component dropComponent) {
        super(dropComponent.getNextComponentPanel());
        this.dropComponent = dropComponent;
    }

    /**
     * Defines the operation when a component is dropped
     *
     * @param context DragContext for the drop
     */
    @Override
    public void onDrop(DragContext context) {
        dropComponent.getNextComponentPanel().setWidget(context.draggable);
        super.onDrop(context);
        dropComponent.onComponentAdded();

    }

    /**
     * Don't drop if there is already a component here
     *
     * @param context DragContext for the drop
     * @throws VetoDragException thrown to prevent dropping
     */
    @Override
    public void onPreviewDrop(DragContext context) throws VetoDragException {
        if (dropComponent.getNextComponentPanel().getWidget() != null) {
            throw new VetoDragException();
        }
        super.onPreviewDrop(context);
    }

}
